Bare electronic chips typically need to be housed in a package that provides an electrical connection between each external electrical contact on the chip to an external electrical contact or terminal of the package, such as, a package connector, pin or ball that allows electrical connection of the package to further external circuitry, such as a printed circuit board. Electrical contacts or pads situated on the top face of the chip typically facilitate electrical continuity between the circuit side of the interior of the chip to the external packaging connections of the chip. Electrical continuity between the pads on the top face of the chip to the package terminals is enabled through interconnect technology, such as wirebond or flip-chip.
A package may have a non-conductive substrate (such as a plastic film or layer) with conductive traces (wires) on or in a surface of the substrate. Typically, either flip-chip connections or wirebond may connect a chip to the package. Some packages include multiple chips, such as one or more logic or processor chips, one or more communications chips (such as for a cell phone or wireless LAN), and/or one or more memory chips, such as a FLASH-type reprogrammable non-volatile memory. Optionally, a cover or encapsulant is used to enclose the chip or chips.
Wirebond packages and flip-chip packages may be used to package one or more integrated circuit (IC) die. In a wirebond package, an upper surface of a wirebond die is coupled to an upper surface of a wirebond package substrate. The chip or die bottom surface or face, opposite to the die top face with the electrical contacts, is first attached to the top face of a wirebond substrate and then connected to the package by fine wires to electrically connect the contacts or pads at the top face of the wirebond die to corresponding electrical contacts of the top face of the wirebond package substrate. In contrast, in a flip-chip package, the chip or die is first inverted or flipped such that the top face of the die faces corresponding contacts on the top face of the substrate and electrical continuity between the die and the substrate is achieved through electrical interconnects, such as solder or copper bumps, to connect the top face of a flip-chip die to the top face of the substrate.